The present invention relates to shoe soles, especially those made entirely from layers of natural fiber.
The prior art describes many forms of shoe soles. Typically, a shoe sole must be impervious to water for the comfort of the wearer. Where the user's foot is enclosed by a shoe top and a water impervious shoe sole, the water impervious layer traps the heat of the wearer's foot. In hot and humid climates, a user wear such shoes and suffer great discomfort from overheated feet. It is critical in such climates that water and air flow relatively freely through the shoe soles so that heat from a user's foot can escape the inside of the shoe.
Many shoes have a water impervious outer shoe sole with a porous inner shoe sole. These shoes are only partly effective in reducing a user's discomfort. In use, a user's weight is focused on a small surface area of the soles of the user's feet. Therefore, the user's foot necessarily compresses a porous inner sole necessarily reducing the porosity of the material. When the porosity of such an inner sole is effectively blocked off, the sole of the user's foot cannot exchange heat by convection through the shoe sole. A user's foot continues to work amidst trapped heat and perspiration within a shoe.
Contrary to this understanding, U.S. Pat. No. 6,665,955 describes a shoe sole having a water impervious inner sole and a textile outer sole. This appears to give a user the worst of all possible worlds.
U.S. Pat. No. 6,593,966 describes shoes with an inner sole of relatively light fleece water impervious shoe soles. desire a shoe sole that is cooler because such a sole is potentially water absorbing. the discomfort of having wet feet because of a non-water resistant shoe sole can be. Such a shoe sole must incorporate a layer that is impervious to
Some varieties of cereals, such as barley, maize, millet, wheat, milo, rice and sorghum nearly completely consist of amylopectin. A common feature of adhesives from these cereals is water solubility. For some products, such as wallpaper glue, water solubility is desired and grain-derived pastes provide such easy solubility.
U.S. Pat. No. 6,162,966 states:                By cereals particularly monocotyledonous plants belonging to the order Poales, preferably those of the family of Poaceae are to be understood. Examples of such plants are plants belonging to the genera Avena (oats), Triticum (wheat), Secale (rye), Hordeum (barley), Oryza (rice), Panicum, Pennisetum, Setaria, Sorghum (millet), Zea (maize) etc. . . . A major field of application is, for instance, in the adhesive industry, where the fields of application are subdivided into four areas: the use as pure starch glue, the use in starch glues prepared with special chemicals, the use of starch as an additive to synthetic resins and polymer dispersions as well as the use of starches as extenders for synthetic adhesives. 90% of all starch-based adhesives are used in the production of corrugated board, paper sacks and bags, composite materials for paper and aluminum, boxes and wetting glue for envelopes, stamps, etc.        
It is well known to use all or a part of millet for an adhesive, even for gluing sheet layers together to make products like cardboard. However, these adhesives are not usable where they will be exposed to liquid water.
U.S. Pat. No. 5,840,309 states:                Dextrins are used for numerous industrial applications. Some examples of relevant areas are the adhesive industry, the paper industry, the pharmaceutical industry, the mining industry, the food industry, and the textile industry. Sometimes a distinction is made between malto-dextrins and pyrodextrins. The first being the product of dextrinization of starch using an enzyme; the latter being the product of dextrinization of starch using heat [including treating millet with heat]. The large scale production of dextrins for non-food applications primarily concerns pyrodextrins.        
The pyrodextrins formed from the amylopectins in millet can be made less soluble in water if combined with other components such as polymers. Unless changed in that way, a millet-based glue is certain to fail when exposed to water.
That idea was discussed in U.S. Pat. No. 4,915,766:                The resin also typically will include thickeners, fillers and extenders. Powdered vegetable materials such as starch, nutshells (for example, walnut shells, pecan shells, coconut shells, ivory nut shells, horse chestnut shells, peanut shells, and the like), wood flours, barks, leaves, corn cob (Co Cob), rice hull and the like are usually mixed into the adhesive as fillers either alone or in combination with a diluent such as wheat flour (Glu X), sorghum flour and the like for preventing over penetration of adhesive into the wood veneer, for retaining a uniform adhesive viscosity to facilitate the spreading of the adhesive on the veneer surface, and for preventing the formation of interstices and cracks accompanying the shrinkage and aging of the cured resin after adhesion. Fillers often are used in an amount of from about 8 to 14% based on the weight of the phenolic resin.        
Millet in that case is used only as a filler for the primary adhesive to glue layers of wood together.
U.S. Pat. No. 6,083,586 states:                The term “sheet” as used in this specification and the appended claims is intended to include any substantially flat, corrugated, curved, bent, or textured sheet made using the compositions and methods described herein. The only essential compositional limitation is that the binding matrix comprises starch formed by gelatinizing starch granules during the sheet-making process. The starch-bound sheets may include organic coatings, printing, other sheets laminated thereto, etc. The starch-based sheets are preferably non-frangible such that they are not easily shattered. When starch is included in high enough amounts the resultant sheets are inherently not frangible or easily shattered. . . . Although starch is produced in many plants, the most important sources are seeds of cereal grains, such as corn, waxy corn, wheat, sorghum, rice, and waxy rice, which can also be used in the flour and cracked state.        
The '586 patent indicates a desirable feature of starch bound sheets. They are not frangible or easily shattered. There is a need for a method and product by which the benefits of starch-based adhesives without water solubility.